Nanocomposite thin film structures based on polyarylenephthalide with SWCNT and graphene oxide fillers

Investigations of nanocomposite thin films based on polyarylene- phthalide, single-walled carbon nanotubes and graphene oxide have been carried out. Using these films as a transport layer, field-effect transistors were assembled and their output and transfer characteristics were measured. The mobility of charge carriers was estimated and the obtained values are as follows: μ_PAP/GO = 0.020 cm² V^?1 s^?1 and μ_PAP/SWCNT = 0.071 cm² V^?1 s^?1.     

Ion mobility spectrometry of talarozole, a new azole drug, in cleaning quality control

Ion mobility spectrometry (IMS) gains increased pharmaceutical interest as an analytical technique for the verification of equipment cleaning. Using a fractional factorial design, we developed an IMS method for talarozole, which represents a new generation of retinoic acid metabolism blocking agents (RAMBA) that can be used for the treatment of different dermatological diseases, such as psoriasis and acne. Using a Smiths Detection Ionscan-LS and the optimal IMS settings obtained, talarozole showed a drift time of 16.648 ms, corresponding to a reduced ion mobility K₀ of 1.072 cm²V^?1s^?1. Total analysis times below 1 min were achieved. Talarozole was well separated in the plasmagram from other azole compounds and the limit of detection was found to be 43 ng/ml. Swab samples collected from steel and glass plates were successfully analyzed, thereby showing that IMS is indeed a suitable technique for the quantitative analysis of talarozole in cleaning quality control.     

Preparation of polymers having hole and electron transport units by Friedel–Crafts reaction

Polymers having 2,5‐diphenyl‐1,3,4‐oxadiazole (BCO) or anthracene (BCA) as an electron transport unit and N,N′‐diphenyl‐N,N′‐bis(4‐butylphenyl)‐benzidine (BTPD) as a hole transport unit were prepared by condensation polymerization using Friedel–Crafts reaction. It was found that BCO was less reactive than BCA. The low reactivity of the BCO monomer can be explained by the oxygen atom in the oxadiazole unit, which acts as a Lewis base and reduces the activity of the catalyst. The redox behavior measured by cyclic voltammetry showed for both BTPD‐BCO and BTPD‐BCA almost the same oxidation potential. In addition, the BTPD‐BCO also exhibited a reduction peak. Hole and electron drifts mobility of the polymers were measured by the time‐of‐flight method. The hole drift mobility of both BTPD‐BCO and BTPD‐BCA was 7.4 × 10^?5 cm² V^?1 s^?1. The electron drift mobilities of BTPD‐BCO and BTPD‐BCA were 6.5 × 10^?5 cm² V^?1 s^?1 and 5.2 × 10^?6 cm² V^?1 s^?1, respectively. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3083–3089, 2007     

An A‐D‐A′‐D‐A Conjugated Molecule Entailing Diazapentalene Unit for an n‐Type Organic Semiconductor

Conjugated molecules with low lying LUMO levels are demanding for the development of air stable n‐type organic semiconductors. In this paper, we report a new A‐D‐A′‐D‐A conjugated molecule ( DAPDCV ) entailing diazapentalene (DAP) and dicyanovinylene groups as electron accepting units. Both theoretical and electrochemical studies manifest that the incorporation of DAP unit in the conjugated molecule can effectively lower the LUMO energy level. Accordingly, thin film of DAPDCV shows n‐type semiconducting behavior with electron mobility up to 0.16 cm²?V^?1?s^?1 after thermal annealing under N₂ atmosphere. Moreover, thin film of DAPDCV also shows stable n‐type transporting property in air with mobility reaching 0.078 cm²?V^?1?s^?1.     

Effect of thiophene spacers in benzodithiophene‐based polymers for organic electronics

Poly{2,6‐bis(thiophene‐2‐yl)‐4,8‐bis(5‐dodecylthiophen‐2‐yl)benzo[1,2‐b :4,5‐b' ]dithiophene} [poly(Th‐bDTBDT‐Th)] was successfully synthesized through Stille coupling polymerization. The addition of the thiophene spacer groups between the benzodithiophene units resulted in improved performance in optoelectronic devices. This was attributed to the reduced lamellae stacking distance in thin film with prominent π–π stacking peak indicating close assembly of poly(Th‐bDTBDT‐Th). Spacing between the benzodithiophene units in poly(Th‐bDTBDT‐Th) helped the close packing of dodecyl chains and generated improved π stacking interaction. For poly(Th‐bDTBDT‐Th), the measured average field effect mobility was 2.32 × 10^?3 cm² V^?1 s^?1 and average hole mobility in vertical direction was 2.92 × 10^?5 cm² V^?1 s^?1. Charge transport in both directions was improved by one order of magnitude with the presence of the thiophene spacer. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 3942–3948     

From Linear to Angular Isomers: Achieving Tunable Charge Transport in Single‐Crystal Indolocarbazoles Through Delicate Synergetic CH/NH⋅⋅⋅π Interactions

Weak intermolecular interaction in organic semiconducting molecular crystals plays an important role in molecular packing and electronic properties. Here, four five‐ring‐fused isomers were rationally designed and synthesized to investigate the isomeric influence of linear and angular shapes in affecting their molecular packing and resultant electronic properties. Single‐crystal field‐effect transistors showed mobility order of 5,7‐ICZ (3.61 cm² V^?1 s^?1) >5,11‐ICZ (0.55 cm² V^?1 s^?1) >11,12‐ICZ (ca. 10^?5 cm² V^?1 s^?1) and 5,12‐ICZ (ca. 10^?6 cm² V^?1 s^?1). Theoretical calculations based on density functional theory (DFT) and polaron transport model revealed that 5,7‐ICZ can reach higher mobilities than the others thanks to relatively higher hole transfer integral that links to stronger intermolecular interaction due to the presence of multiple NH???π and CH???π(py) interactions with energy close to common NH???N hydrogen bonds, as well as overall lower hole‐vibrational coupling owing to the absence of coupling of holes to low frequency modes due to better π conjugation.     

Hybrid phospholipid bilayer coatings for separations of cationic proteins in capillary zone electrophoresis

Protein separations in CZE suffer from nonspecific adsorption of analytes to the capillary surface. Semipermanent phospholipid bilayers have been used to minimize adsorption, but must be regenerated regularly to ensure reproducibility. We investigated the formation, characterization, and use of hybrid phospholipid bilayers (HPBs) as more stable biosurfactant capillary coatings for CZE protein separations. HPBs are formed by covalently modifying a support with a hydrophobic monolayer onto which a self‐assembled lipid monolayer is deposited. Monolayers prepared in capillaries using 3‐cyanopropyldimethylchlorosilane (CPDCS) or n‐octyldimethylchlorosilane (ODCS) yielded hydrophobic surfaces with lowered surface free energies of 6.0 ± 0.3 or 0.2 ± 0.1 mJ m^?2, respectively, compared to 17 ± 1 mJ m^?2 for bare silica capillaries. HPBs were formed by subsequently fusing vesicles comprised of 1,2‐dilauroyl‐sn‐glycero‐3‐phosphocholine or 1,2‐dioleoyl‐sn‐glycero‐3‐phosphocholine to CPDCS‐ or ODCS‐modified capillaries. The resultant HPB coatings shielded the capillary surface and yielded reduced electroosmotic mobility (1.3–1.9 × 10^?4 cm² V^?1s^?1) compared to CPDCS‐ and ODCS‐modified or bare capillaries (3.6 ± 0.2 × 10^?4 cm² V^?1s^?1, 4.8 ± 0.4 × 10^?4 cm² V^?1s^?1, and 6.0 ± 0.2 × 10^?4 cm² V^?1s^?1, respectively), with increased stability compared to phospholipid bilayer coatings. HPB‐coated capillaries yielded reproducible protein migration times (RSD ≤ 3.6%, n ≥ 6) with separation efficiencies as high as 200 000 plates/m.     

A High‐Performance Organic Field‐Effect Transistor Based on Platinum(II) Porphyrin: Peripheral Substituents on Porphyrin Ligand Significantly Affect Film Structure and Charge Mobility

Organic field‐effect transistors incorporating planar π‐conjugated metal‐free macrocycles and their metal derivatives are fabricated by vacuum deposition. The crystal structures of [H₂(OX)] (H₂OX=etioporphyrin‐I), [Cu(OX)], [Pt(OX)], and [Pt(TBP)] (H₂TBP=tetra‐(n‐butyl)porphyrin) as determined by single crystal X‐ray diffraction (XRD), reveal the absence of occluded solvent molecules. The field‐effect transistors (FETs) made from thin films of all these metal‐free macrocycles and their metal derivatives show a p‐type semiconductor behavior with a charge mobility (μ) ranging from 10^?6 to 10^?1 cm² V^?1 s^?1. Annealing the as‐deposited Pt(OX) film leads to the formation of a polycrystalline film that exhibits excellent overall charge transport properties with a charge mobility of up to 3.2×10^?1 cm² V^?1 s^?1, which is the best value reported for a metalloporphyrin. Compared with their metal derivatives, the field‐effect transistors made from thin films of metal‐free macrocycles (except tetra‐(n‐propyl)porphycene) have significantly lower μ values (3.0×10^?6–3.7×10^?5 cm² V^?1 s^?1).     

Electronic structure and microscopic charge‐transport properties of a new‐type diketopyrrolopyrrole‐based material

Recently, diketopyrrolopyrrole (DPP)‐based materials have attracted much interest due to their promising performance as a subunit in organic field effect transistors. Using density functional theory and charge‐transport models, we investigated the electronic structure and microscopic charge transport properties of the cyanated bithiophene‐functionalized DPP molecule (compound 1 ). First, we analyzed in detail the partition of the total relaxation (polaron) energy into the contributions from each vibrational mode and the influence of bond‐parameter variations on the local electron–vibration coupling of compound 1 , which well explains the effects of different functional groups on internal reorganization energy (λ). Then, we investigated the structural and electronic properties of compound 1 in its isolated molecular state and in the solid state form, and further simulated the angular resolution anisotropic mobility for both electron‐ and hole‐transport using two different simulation methods: (i) the mobility orientation function proposed in our previous studies (method 1); and (ii) the master equation approach (method 2). The calculated electron‐transfer mobility (0.00003–0.784 cm² V^?1 s^?1 from method 1 and 0.02–2.26 cm² V^?1 s^?1 from method 2) matched reasonably with the experimentally reported value (0.07–0.55 cm² V^?1 s^?1). To the best of our knowledge, this is the first time that the transport parameters of compound 1 were calculated in the context of band model and hopping models, and both calculation results suggest that the intrinsic hole mobility is higher than the corresponding intrinsic electron mobility. Our calculation results here will be instructive to further explore the potential of other higher DPP‐containing quinoidal small molecules. © 2015 Wiley Periodicals, Inc.     

A Planarized Triphenylborane Mesogen: Discotic Liquid Crystals with Ambipolar Charge‐Carrier Transport Properties

A discotic liquid‐crystalline (LC) material, consisting of a planarized triphenylborane mesogen, was synthesized. X‐ray diffraction analysis confirmed that this compound forms a hexagonal columnar LC phase with an interfacial distance of 3.57 Å between the discs. At ambient temperature, this boron‐centered discotic liquid crystal exhibited ambipolar carrier transport properties with electron and hole mobility values of approximately 10^?3 and 3×10^?5 cm² V^?1 s^?1, respectively.     

Two‐Step direct arylation for synthesis of naphthalenediimide‐based conjugated polymer

A naphthalenediimide (NDI)‐based conjugated polymer was synthesized by a two‐step direct C‐H arylation sequence. In the first step, two ethylenedioxythiophene units were coupled to NDI by direct arylation. In the second step, the direct arylation polycondensation of the monomer, formed in the first step, with 2,7‐dibromo‐9,9‐dioctylfluorene afforded the corresponding NDI‐based conjugated polymer ( PEDOTNDIF ) with molecular weight of 21,500 in 91% yield. The optical and electrochemical properties of the polymer were evaluated. The polymer showed ambipolar behavior in organic field‐effect transistors (OFETs). The electron mobility of PEDOTNDIF was estimated to be 2.3 × 10^?6 cm² V^?1 s^?1 using an OFET device with source‐drain (S‐D) Au electrodes. A modified OFET device with S‐D MgAg electrodes increased the electron mobility for PEDOTNDIF to 1.0 × 10^?5 cm² V^?1 s^?1 due to the more suitable work function of these electrodes, which reduced the injection barrier to the semiconducting polymer. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1401–1407     

Comparable charge transport property based on S…S interactions with that of π-π stacking in a bis-fused tetrathiafulvalene compound

Compact molecular packing with short π-π stacking and large π-overlap in organic semiconductors is desirable for efficient charge transport and high carrier mobility.Thus charge transport anisotropy along different directions is commonly observed in organic semiconductors.Interestingly,in this article,we found that comparable charge transport property were achieved based on the single crystals of a bis-fused tetrathiafulvalene derivative(EM-TTP) compound along two interaction directions,that is,the multiple strong S…S intermolecular interactions and the π-π stacking direction,with the measured electrical conductivity and hole mobility of 0.4 S cm~(-1),0.94 cm~2 V~(-1) s~(-1) and 0.2 S cm~(-1),0.65 cm2 V~(-1) s~(-1),respectively.This finding provides us a new molecular design concept for developing novel organic semiconductors with isotropic charge transport property through the synergistic effect of multiple intermolecular interactions(such as S…S interactions) and π-π stacking.     

Synthesis,Crystal Packing,and Ambipolar Carrier Transport Property of Twisted Dibenzo[g,p]chrysenes

A versatile method for the synthesis of dibenzo[g,p]chrysene (DBC) derivatives based on regio‐ and stereoselective stannyllithiation to diarylacetylenes is described. This method affords a variety of DBCs possessing both electron‐donating and electron‐withdrawing functional groups. These twisted molecules take brickwork packing structures in single crystals. Thus, ambipolar carrier transport properties with mobility values of up to 10^?3 cm² V^?1 s^?1 in the amorphous state were achieved. Functional groups on DBC frameworks are considered to increase carrier mobility through the enhancement of intermolecular interactions in the brickwork packing structures.     

The impedance of solutions of AOT/water micelles in hexane

Broadband dielectric spectroscopy was used to study the electric properties of solutions of reverse AOT/water micelles in hexane. An analysis of the frequency dependences of the complex electric modulus allowed us to find the region of frequencies in which dc-conductivity was observed and exclude the region of electrode effects. At frequencies f of ～ 10⁴Hz, the field dependences of dc-conductivity changed from linear (the Ohm law) to quadratic (the Mott law) as the volume fraction of micelles increased. This was evidence of a strengthening of the effect of current limitation by a volume charge. The upper and lower limits of the drift mobility of carriers μ responsible for dc-conductivity were estimated as 0.1 cm^?2 V^?1 s^?1 < μ < 0.3 cm^?2 V^?1 s^?1, which was close to the mobility of electrons in hexane. This allowed us to relate the nature of current carriers to that of free electrons; the activation energy of electron creation was found to be E _a ≈ 0.41 eV. The electron lifetime up to its trapping by acceptors was estimated. The results obtained and the literature data on the rate constants of such reactions led us to conclude that micelles were capable of absorbing acceptor impurities from solvents (additional solvent purification).     

High‐performance field‐effect transistors based on furan‐containing diketopyrrolopyrrole copolymer under a mild annealing temperature

Two furan‐flanked polymers poly{3,6‐difuran‐2‐yl‐2,5‐di(2‐octyldodecyl)‐pyrrolo[3,4‐c]pyrrole‐1,4‐dione‐alt‐thienylenevinylene} (PDVFs), with a highly π‐extended diketopyrrolopyrrole backbone, are developed for solution‐processed high‐performance polymer field‐effect transistors (FETs). Atomic force microscopy and grazing incidence X‐ray scattering analyses indicate that PDVF‐8 and PDVF‐10 films exhibit a similar nodular morphology with the ultrasmall lamellar distances of 16.84 and 18.98 Å, respectively. When compared with the reported polymers with the same alkyl substitutes, this is the smallest d‐spacing value observed to date. This closed lamellar crystallinity facilitates charge carrier transport. Therefore, polymer thin‐film transistors fabricated from as‐spun PDVF‐8 films exhibit a high hole mobility exceeding 1.0 cm² V^?1 s^?1 with a current on/off ratio above 10⁶. After annealing treatment at 100 °C in air, the highest hole mobility of PDVF‐8‐based FETs was significantly improved to 1.90 cm² V^?1 s^?1, which is among the highest values of the reported FET devices fabricated from polymer thin films based on this mild annealing temperature. In contrast, long alkyl‐substituted PDVF‐10 exhibited a relatively low hole mobility of 1.65 cm² V^?1 s^?1 mainly resulting from low molecular weight. This work demonstrated that PDVFs would be promising semiconductors for developing cost‐effective and large‐scale production of flexible organic electronics. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1970–1977     

Effects of silica nanoparticle addition on polymer semiconductor wettability and carrier mobility in solution‐processable organic transistors on hydrophobic substrates

The effects of the addition of silica nanoparticles (SNPs) on wettability of regioregular poly(3‐hexylthiophene) (P3HT) organic semiconductor solutions on hydrophobic substrates and the carrier mobility in organic field‐effect transistors (OFETs) made of these films are investigated. The dewetting of films made from P3HT solutions on hydrophobic substrates modified with octadecyltrichlorosilane (ODTS) is markedly suppressed after the addition of SNPs with phenyl surfactants. This enables us to fabricate continuous P3HT/SNPs films with high crystallinity by the conventional spin‐coating technique, leading to higher mobility compared with P3HT FETs fabricated on non‐modified substrates. Moreover, the addition of SNPs with larger diameters compensates for the degradation of mobility associated with the increase in the concentration of SNPs. Solution‐processed P3HT/SNPs FETs on ODTS‐modified substrates exhibit a field‐effect mobility of 1.3 × 10^?2 cm² V^?1 s^?1, which is almost comparable to that of P3HT FETs without SNPs (2.1 × 10^?2 cm² V^?1 s^?1). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 509–516     

An Azulene‐Containing Low Bandgap Small Molecule for Organic Photovoltaics with High Open‐Circuit Voltage

A simple azulene‐containing squaraine dye ( AzUSQ ) showing bandgap of 1.38 eV and hole mobility up to 1.25×10^?4 cm² V^?1 s^?1 was synthesized. With its low bandgap, an organic photovoltaic (OPV) device based on it has been made that exhibits an impressive open‐circuit voltages (V_oc) of 0.80 V. Hence, azulene might be a promising structural unit to construct OPV materials with simultaneous low bandgap, high hole mobility and high V_oc.     

Alternating Tetrafluorobenzene and Thiophene Units by Direct Arylation for Organic Electronics

Direct arylation represents an attractive alternative to the conventional cross‐coupling methods because of its step‐economic and eco‐friendly advantages. A set of simple D–A oligomeric molecules ( F‐3 , F‐5 , and F‐7 ) by integrating thiophene (T) and tetrafluorobenzene (F4B) as alternating units through a direct arylation strategy is presented to obtain high‐performance charge‐transporting materials. Single‐crystal analysis revealed their herringbone packing arrangements driven by intensive C?H???π interactions. An excellent hole‐transporting efficiency based on single‐crystalline micro‐plates/ribbons was witnessed, and larger π‐conjugation and D–A constitution gave higher mobilities. Consequently, an average mobility of 1.31 cm² V^?1 s^?1 and a maximum mobility of 2.44 cm² V^?1 s^?1 for F‐7 were achieved, providing an effective way to obtain high‐performance materials by designing simple D–A oligomeric systems.     

Temperature‐Independent Hole Mobility of a Smectic Liquid‐Crystalline Semiconductor based on Band‐Like Conduction

A liquid‐crystalline (LC) phenylterthiophene derivative, which exhibited an ordered smectic phase at room temperature, was purified by vacuum sublimation under a flow of nitrogen. During the sublimation process, thin plates with sizes of 1 mm grew on the surface of the vacuum tube. The crystals exhibited the same X‐ray diffraction patterns as the ordered smectic phase of the LC state that was formed through a conventional recrystallization process by using organic solvents. Because of the removal of chemical impurities, the hole mobility in the ordered smectic phase of the vacuum‐grown thin plates increased to 1.2×10^?1 cm² V^?1 s^?1 at room temperature, whereas that of the LC precipitates was 7×10^?2 cm² V^?1 s^?1. The hole mobility in the ordered smectic phase of the vacuum‐sublimated sample was temperature‐independent between 400 and 220 K. The electric‐field dependence of the hole mobility was also very small within this temperature range. The temperature dependence of hole mobility was well‐described by the Hoesterey–Letson model. The hole‐transport characteristics indicate that band‐like conduction affected by the localized states, rather than a charge‐carrier‐hopping mechanism, is a valid mechanism for hole transport in an ordered smectic phase.